1. Field of the Invention
The present invention relates to an automatic sheet-materal feeder, and more particularly to a sheet-material transporting device adapted to prevent a state in which a plurality of ultra thin sheets of paper are fed in a superposed or overlapping state (hereafter feeding in this state will be referred to as the overlapped feeding), as well as an automatic sheet-material feeder equipped with the sheet-material transporting device.
2. Description of the Related Art
A conventional automatic sheet-material feeder is shown in FIG. 13. In this apparatus, a retarding member 74 is disposed such that an opposing surface 72 thereof is located in proximity to an outer peripheral surface of a separation roller 70, which is rotated by an unillustrated driving means, and in such a manner as to extend in the axial direction of the separation roller 70 (i.e., in a direction perpendicular to the plane of the drawing of FIG. 13). A paper guide 76 extending in the axial direction of the separation roller 70 is attached to a side of the retarding member 74 to which the leading end of each document 56 placed on a hopper 78 is fed.
The hopper 78 in which the documents 56 are placed is moved by an unillustrated transfer mechanism to a position at which an uppermost one of the documents 56 is nipped by the paper guide 76 and the separation roller 70. As the separation roller 70 rotates, the uppermost one of the documents 56 is fed by a frictional force through the rotation of the separation roller 70, and is supplied to an unillustrated rotary camera for microfilm photographing, or the like.
In this case, the overlapped feeding of the documents 56 is prevented by adjusting a gap between the outer peripheral surface of the separation roller 70 and the opposing surface 72 of the retarding member 74, an angle at which the retarding member 74 is disposed, and an angle at which the document 56 is fed into a nip between the retarding member 74 and the separation roller 70.
According to the above-described prior art, however, in a case where the documents 56 of varying thicknesses or the documents 56 of different paper quality (e.g. in the coefficient of friction) are present in a mixed form, it is difficult to properly set the aforementioned gap and the like, so that the overlapped feeding of the documents 56 is unavoidable.
In addition, if a leading (inserting-side) end of the document 56, i.e., the retarding member 74-side end thereof, becomes deformed and corrugated, as shown in FIG. 14, there is the problem that trough portions 56A abut against a bent portion 76A of the paper guide 76, with the result that buckling occurs. In addition, if buckling occurs in this manner, the document 56 is jammed between the retarding member 74 and the separation roller 70, or the document 56 is wrapped around the separation roller 70, thereby making it impossible to transport the documents 56.